Organization having adjustable screw-threaded member



A ril 26, 1949. E. JOHNSON 2,463,333

ORGANIZATION HAVING ADJUSTABLE SCREW THREADED MEMBER Filed April 26, 1947 2 Sheets-Sheet 1 ZSnventor Edward! .Jofinson M1 MA (Ittornegs Fig.7

April 1949- E. L. JOHNSON 2,468,333

ORGANIZATION HAVING ADJUSTABLE SCREW THREADED MEMBER 2 Sheets-Sheet 2 Filed April 26, 1947 m5 m 3 a 6 JM 7 MM d/ EM Patented Apr. 26, 1949 ORGANEZA'EION HAVING ADJUSTABLE SGREWT-THREADED MEMBER Edward L. Johnson,

South Qrange, N. J., assi-gnor to T118 Palnut Company,

Irvin-gton, N. 1., a

corporation of New Jersey Application April 26, 1947', Serial No. 744,094

3- Claims. (C1. 74-4248) Wise, if there be two inductively coupled windings, transformer e. gtwo coaxially superimposed windings, the couplingbetween the two windingsmay be varied by varying the telescopic. relation between. them. and a, ferrous core which is common to the two windings.

Wohlhieter Patent 2,386,732 discloses an adjustable inductance device in which \ifindings on a tube of fiber or the like are influenced by tele scopically adjusting a ferrous core which is posi tioned within the tube; While this patent shows two transformer windings on the tube, the arrangement could be used where the tube carried only a single winding. it being desired to vary the inductance of the windings. In the Wohlhieter patent the core is adjusted by means of a threaded stem which is engaged by stationary female thread means; the female thread means being a series of helical'ly disposed spring: fingers, of thin sheet metal, which enter the thread of the stem. To hold the stem in adjusted position, the tips of the spring fingers yield ingl'y' engage the root. of the thread on the stem in a manner that-is well known.

The. capacity of the spring fingers to yield outwardly of the axis of the threaded stem is relatively small. Therefore, for the female-thread means of the Wohlhieter patent to satisfactorily hold the stem in adjustedposition, the actual root diameter of the threaded stem must bequite close to the nominal diameter for which the female thread means is designed. With a die-threaded stem this. presents no problem in actual practice. However, most of the threaded stems and other machine screws which are available nowadays, have the threads formed by a rolling procedure The rolled threads available on the market may vary so much, from the nominal size as to cause dii'culty' when used as in the Wohlhieter patent. Out of av quantity of stems, some may have too tightafit, and some tOoIoOse a fit, in the female thread means.

An object of the present invention is to provide an adjustable inductance device, of the generalv type disclosed inthe Wohlhieter patent, which functions satisfactorily with threaded stems hav- 2 ingsize variations of the magnitude that are likely to be found in rolled threads.

Another object of the invention is to provide an adjustable inductance device, or mechanically analogous assembly, in which an undersize: threaded stem or screw may be adjusted in female thread means and. be automatically heldin adjusted position.

An additional object oi the invention is to pro vide an adjustable inductance device, or mechani-- cally analogous assembly. in which an undersizev threaded stem or screw may be. adjusted in female thread means and be y-ieldingly engaged thereby to hold the stem or screw in adjusted position.

A further object oi the invention is to cause female thread means. to. yieldingly engage and hold. an interengaged male thread which is un-- dersize as compared to the female thread.

A still further object of the invention is to provide a screw threaded assembly in which male threads having substantial. variations from the. nominal size will be. satisfactorily received by the female thread means. and be irictionally held against fortuitous rotation.

A still further object of the invention is to provide a screw threaded organization. in which a standard, male thread. is received. by standard thread engaging, means in the form of thin spring fingers which enter the thread, and the spring fingers are caused to make yielding engagement with the wall surface of the male thread.

Various additional objects. and advantages, and objects relating to details. and economies of con-- struction, operation and use. willbeapparent from.- the detailed description which follows.

My invention is clearly defined in. the appended claims. Where parts are, for clarity and convenience,.referredto onthebasis of their oriented position shown in the accompanying drawing, no limitation. as to positioning, of the entire struc ture. is to be implied, since. it will be understod thatthe entire structure. may be inverted or that it may be. used in. any inclined position. Also in both the description and the. claims. parts at times may be identified by specific names for clarity and convenience,. but. such nomenclature is to, bev understood as having the broadest meaning consistent with. the context. and with the concept of my invention asdistinguished from the pertinent prior art. The best form in which I have contemplated applying. my invention is illustrated in the accompanying drawing forming part of this specification,v in which:

Fig. 1. is a perspective view showing a stamped spring metal member which is adapted to support an inductance tube and make threaded engagement with the stem of the core.

Fig. 2 is a vertical sectional view showing the member of Fig. 1 installed in a plate-like section of a radio chassis and mounting an intermediate frequency transformer, or the like, provided with an adjustable iron core.

Fig. 3 is a view similar to Fig. 2 but with the transformer tube, or inductance tube, merely indicated and the core and stem shown in the position which they would assume in the absence of the tube. I

Fig. 4 is a greatly enlarged plan View showmg plan the female thread portion, or thread engaging portion, of the member of Fig. 1.

Fig. 5 is a largely diagrammatic sectional view showing a threaded stem, or machine screw, coaxially approaching female thread means such as shown in Fig. 4, the pitch of the male and female threads being related as contemplated by the present invention.

Fig. 6 is a largely diagrammatic view similar to Fig. 5 showing how the male and female threads cooperate.

Fig. 7 is a plane development showing the relationship between the Referring to Fig. 1, a member designated as a whole by I is a stamped one-piece clamp or fastener preferably formed from spring sheet steel, hardened and tempered.

to provide opposed arcuate clamp members I2, I 2 and oppositely positioned latch members I3, l3 (see also Figs. 2 and 3). Near their upper ends each vertical edge of the clamp members l2, I2 is provided with a sharp projecting tooth [4. From the upper ends of clamp members I2, I2 wings I 5, 15 project outwardly and somewhat downwardly, one wing being provided with a downwardly projecting finger I 6. Across the bottom These fingers are disposed in thread relationship, the tips of means of which the core is telescopically adjustable within the tube 20. The thread of the stem is entered and engaged by the four spring fingers 18 shown in Fig. 1.

The clamp I0 is adapted Upon the assembly being the hole 23 the Wings I5, I

wardly, thereby biasing the upper extremities of inwardly and causing to firmly grip the tube 20.

The finger I6 enters one of two secondary holes 21, 21 in the plate 26 to prevent rotation of the assembly. In the fully seated position shown in Fig. 2 latch members [3, I3 spring outwardly beneath the Plate 26, the tips of the latch members engaging the under-surface of the plate and preventing withdrawal of the assembly from the hole 26 unless the latch members l3, l3 be specially retracted for removal of the assembly.

The construction of the clamp of Fig. 1 and Wohlhieter patent resides in the teeth l4. These are inclined inwardly from the circumference established by arcuate clamp members l2,

of the female thread formed by the teeth I8 is thread of stem 25 as wil1 presently be explained.

Referring to Fig. 4, there is shown in greatly enlarged plan view the center portion of the web I! of clamp II). In Fig. 4 the individual teeth of the female thread are designated as l8a, I81), I and id. Since the tips of these teeth lie on a. helix, tooth l8b will be at 29 such as stem 25, a machine screw, a bolt, or the like. The thread of member 29 has crest 30, root 3| and wall 32. As shown in Fig. 5, the pitch of the thread of screw 29 is greater than the pit-ch of the thread established by the spring fingers I81: and

s. The teeth thread of the contains the teeth Fig. 6 shows in dotted lines the position that the teeth I 8a and I8b will occupy relative to the screw when the screw; been advanced two turns through the web wardly and tooth These teeth will now exert spring pressure upon the wall 32 lationship, the tips of teeth I80, I81), 180 and 18d are disposed as shown on dotted lines. The pitch of the thread on screw 29 being greater than the pitch of the female thread established by teeth l8a-l8d, the development of one convolution of the helix of the male thread (at the radius at which the tips of the teeth l8a-l8d would contact it if they could) is as shown by the line 31. For the teeth l8al8d to mate with the male thread helix 31, it will be necessary that the axis 35 of th male thread member be tilted to the right sufiieiently to eliminate the angle and bring line 31 into coincidence with the dotted lines I8a-l8d.

Fig. 3 illustrates in exaggerated degree the position which screw 25 and core 24 will assume under the influence of the female thread in web 11 when left free to do so. However, due to the yielding nature of thread engaging teeth l8a [8d, the transformer tube may be readily forced into axially aligned position with the axis of the female thread in web H, to bring the parts into the relationship shown in Fig. 2. While Fig. 3 shows the clamp I0 already installed in the plate 26, the tube 20 of course may be inserted into the clamp Ill before the assembly is mounted in the plate 26, as shown in Fig. 2.

It will be seen that the teeth l8al8d exert a canting force upon the stem thereby biasing the core 24 into frictional engagement with the This frictional engagement wall of the tube 20. prevents fortuitous rotation of stem 25 and thereby serves to maintain the core 24 in telescopically adjusted position in the tube. Also, tube 20 constitutes a means to limit, even substantially prevent or eliminate, canting movement of the screw in response to the canting force imparted by the female thread. As a result of such limitation on the canting movement of the screw, the fingers of the female thread are flexed and resiliently engage the wall of the male thread. The frictional holding force on the male thread is cumulative with the frictional holding force established between core 24 and the wall of tube 20 to hold the core 24 in adjusted position.

The optimum value of angle 3 depends upon various circumstances. With relatively small clearance between core 24 and tube 20 (.005 to .008") the angle s may be 2 or 3". With larger clearances between the core and the tube, a large angle 3 would be required, in some cases an angle of 5 or 6. The specific pitches selected for the male and the female thread will also vary with the circumstances and the use to which the invention is put. In some cases I have combined a screw having 32 threads to the inch with a female thread of 44. threads to the inch. Also I have combined a screw having threads to the inch with a female thread of 48 threads to the inch.

While I prefer that the pitch of the screw be greater than the pitch of the female thread, a like result can be obtained Where the pitch of the screw is less than that of the female thread. Referring to Fig. '7, and assuming that the pitch of the screw were less than that of the female thread, the line 31 would lie below the line of teeth lint-48d. Then by tilting the axis 35 of the screw to the left, the line 31 would be brought into coincidence with the line of teeth Ilia-I811. However, the use of a lesser pitch on the screw requires non-standard threads, whereas standard threads may be used where the pitch of the screw is greater than that of the female thread.

A similar result could also be obtained with male and female threads of the same pitch, the clamp it! being so stamped that the axis of the female thread was tilted with respect to the axis of tube 20. In quantity production, however, this would require special and difficult gaging and inspection procedure.

I claim:

1. In an organization in which a member provided with a male thread is engaged by sheet metal spring fingers which are disposed in thread relationship and enter the male thread, the improvement which comprises the pitch at which the fingers are disposed being less than the pitch of the male thread whereby the fingers exert a canting force on said member, there being means which engages said member and at least limits the canting movement thereof with resultant fiexure of the fingers, the fingers thereby resiliently engaging the wall of the male thread and resisting fortuitous rotation of said member, and the engagement between said means and said member also resisting fortuitous rotation of said member.

2. In an organization in which a member pro.- vided with a male thread is engaged by sheet metal spring fingers which are disposed in thread relationship and enter the male thread, the improvement which comprises the pitch at which the fingers are disposed being less than the pitch of the male thread whereby the fingers exert a canting force on said member, there being means which engages said member and at least limits the canting movement thereof with resultant flexures of the fingers, the fingers thereby resiliently engaging the wall of the male thread and resisting fortuitous rotation of said member.

3. In an organization in which a member provided with a male thread is engaged by resiliently yieldable female thread means, the improvement which comprises the female thread means having a different pitch from the pitch of the male thread whereby the female thread means exerts a canting force on said member, there being means which engages said member and at least limits the canting movement thereof with resultant yielding of the female thread means, the female thread means thereby resiliently engaging the male thread and resisting fortuitous rotation "of said member.

EDWARD L. JOHNSON.

REFERENCES CITED UNITED STATES PATENTS Number Name Date Wohlhieter Oct. 9, 1945 Certificate of Correction Patent N 0. 2,468,333. April 26, 1949.

EDWARD L. JOHNSON It is hereby certified that error appears in the printed specification of the above numbered patent requiring correctlon as follows:

Column 6, line 42, claim 2, for the word flexures readflewm'e;

and that the said Letters Patent should be read with this correction therein that the same may conform to the record of the case in the Patent Ofiice.

Signed and sealed this 4th day of October, A. D. 1949.

THOMAS F. MURPHY,

Assistant Uommissioner of Patents. 

